555- 4017 project

Discussion in 'The Projects Forum' started by ram4461, Mar 21, 2014.

  1. ram4461

    Thread Starter New Member

    Mar 21, 2014
    I'm trying to get my circuit to work. I was given a working schematic and designed the PCB in ulitboard so i believe the design of my circuit is correct. However when I soldiered r everything together and tested it only LED number 1 comes on and stays on but the LEDs are meant to come one one by one. I checked all my solider joints and think they are fine. any suggestions would be great. thanks
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Check the group of three copper traces that run parallel to each other on the bottom of the board, right side running horizontal on your photo. It looks like you may have a mess of un-etched copper connecting all of them together. Either that or a weird reflection in the photo.

    Other than that, I did not bother to check if all of your connections are correct. But one thing is for sure, you need to clip the long leads on the back of the board to make sure they are not shorting each other.

    The other possibility is that the 555 does not go low enough (close enough to zero volts) to trigger the 4017.

    Good luck.
  3. magnet18

    Senior Member

    Dec 22, 2010
    welcome to debugging!

    the checklist I live by for the first 5 things-
    1, is it plugged in
    2, are all chips in the sockets
    3, are all chips the correct orientation
    4, are they the correct chips
    5, repeat 2-4 for all transistors

    solves 90% of my issues, no joke :p

    after that start chasing traces, check each pin of each chip first and make sure it's doing what is expected of it

    do you have access to a scope?
  4. nerdegutta


    Dec 15, 2009
    How do you reset the 4017 chip?

    Edit: Oh, so the IC start all over when one cycle is done...

    Attached is one setup I used for a project. With this you could add 2 more LEDS and connect PIN 6 to PIN 15. When the circuit is running, and the IC has reach LED 6 on PIN 1, it resets itself to start over.

    Also, as mentioned, check the horizontal traces with a DMM.
    Last edited: Mar 22, 2014
  5. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    hi ram,
    If the 555 is not running the 4017 will remain on pin #3, [LED1].

    Connect a test LED on pin 3 of the 555, it should flash, if not the problem is with the 555 connections.

    Also as suggested previously, first crop off those excess component wires.

  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    Crop all the soldering, and it looks as pins 14(clock), 15(reset) maybe shorting out, which will keep resetting the counter to put the first led on.
  7. MrCarlos

    Active Member

    Jan 2, 2010
    Hello ram4461

    There are several things to improve in your circuit:

    Remove resistor R15 connected from the PIN 3 at 555 till the PIN 14 of 4017. is not necessary, in its place install a jumper.

    probably also have problems with MR PIN entry in the 4017 14.
    resistor R16 has a very high value (100K) could be replaced by a 10K. resistor.

    you have to analyze the data sheets of both the transistor and the LED you use in your circuit to determine the value of all the necessary resistors for the LED lights.

    To the transistor are of particular importance Ib and VCE (sat) parameters.
    For the LED are particularly important parameters Vf and If.
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    Some of the traces in the top right section of the second pic appear to be discontinuous/ etched away ? Or is that just an artifact of the pic?
  9. KJ6EAD

    Senior Member

    Apr 30, 2011
    C3 and R16 are not needed. Master reset can be tied directly to ground.